We Energies
Quality Management and
Beneficiation Processes
for the Use of CCPs in
Construction Materials
Bob Meidl, We Energies CCP Group
UWM-CBU Workshop on Green Construction
Materials Using Coal Combustion Products
May 1-2, 2008
CCP Producing Plants
CCP Quality Focus
z
Largest quantities of Coal Combustion
Products (CCP) produced by We Energies
and most other coal power plants:
– Fly Ash
– Bottom Ash
– Flue gas desulfurization (Scrubber) products
z
Fly Ash and FGD products have greatest
chance of being impacted by current and
future plans
Fly Ash Contracts and Quality Control
z
We Energies has contracts with fly ash
management companies to provide
marketing, sales, distribution and quality
control services.
-Lafarge
-Mineral Resource Technologies
Quality of CCP’s – Fly Ash
z
Regular/routine sampling of fly ash
z
Importance of Consistency – routine tests
– Loss on Ignition (LOI – carbon content)
– Foam Index (impact of carbon)
– Fineness (particle size - reactivity)
– Ammonia content (if necessary)
z
Performance testing of fly ash to meet
specifications and standards of end users
(ASTM C618)
LOI (Loss on Ignition)
z
z
z
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LOI is an indication of the carbon content.
Small sample of fly ash is ignited at 750 ± 50
degrees C.
The loss in mass is expressed as a percentage
of the total initial mass.
ASTM C 618:
6.0% max
12% for class F based on acceptable service
records or lab testing.
In real practice, fly ash used in most concrete
in the upper Midwest has LOI below 2%.
Foam Index
z
Measures how the carbon in fly ash may
impact air entraining agents.
z
Each ash source has a foam index limit.
z
LOI may not change but foam index could
fluctuate.
z
Consistency is important to end user.
Effects of Carbon in Fly Ash for
Concrete
z Impact
air entraining
z Impact freeze/thaw durability
z Admixture quantities
z Color
z Water demand and strength
Fineness
z
Amount retained on #325 sieve
z
Amount retained considered too coarse to
react.
z
ASTM C 618: 34% maximum retained.
Strength Activity & Water
Requirement
z Mortar
cubes vs. cement control
– 20% fly ash by weight, equal flow
– water requirement as a percent of the control
calculated
z ASTM
C618
– Strength Activity, min. % of control: 75% of
control at 7 or 28 days (meeting 7 days
satisfies C618)
– Water Requirement, max. % of control: 105
Potential Impacts to CCP
Quality and Availability
z Coal
source: Where did it come
from? How consistent?
z Plant equipment age, maintenance
and reliability
z Operator decisions
z Air Quality Control Systems
– Emission reductions (NOx, SOx,
Mercury)
Should the tail wag the dog?
Coal Source:
Coal Source:
Class C Fly Ash
z
z
z
z
Produced from burning sub-bituminous
(western) coal
Higher calcium oxide content, lower silicate
content
Not only pozzolanic, but has cementitious
properties as well
Concrete quality Class C fly ash currently
produced at We Energies Oak Creek, Pleasant
Prairie and Presque Isle Power Plant
Coal Source:
Class F Fly Ash
z
z
z
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Produced from burning bituminous
(eastern) coal
Lower calcium oxide content, higher silicate
content
Has pozzolanic properties in concrete
mixtures (not cementitious on its own)
Expecting concrete quality Class F fly ash
from the new Oak Creek units under
construction
We Energies Coal Procurement
Coal source based on economics and
emissions limits:
z
z
z
z
Evaluate coal sources for potential impacts on
CCP quality
Involve Fly Ash Management company
Plan test burns and segregate CCP as necessary
for evaluation
Sample, test and determine actual impacts on
CCP quality and manage accordingly
Plant Equipment, Maintenance and
Operator Decisions
Challenges to ash quality:
z
Poorly maintained equipment (coal pulverizers/burners)
can negatively impact fly ash
z
Boiler Operators may have varying priorities/goals while
operating (max load, emission limit, reliability)
z
Inability to segregate or manage poor quality fly ash
Plant Equipment, Maintenance and
Operator Decisions
We Energies approach:
Utilize fly ash quality feedback to plan maintenance needs and
make operational adjustments
z
Educate plant operators on CCP use and value (training)
– Make quality data available to them
z
Involve fly ash management companies on site
z
Segregate lower or suspect quality fly ash
– Ability to direct ash to specific silos or storage and
manage end use
z
Maximize quality of CCP while balancing various priorities
Quality Feedback
Changing Power Plant Landscape
z Regulations
and efforts to decrease
plant emissions are changing power
plants
Fear, barriers to CCP utilization…
z What is being done at the plant that
creates my CCP materials?
Older Model
z Burn
coal
z Make electricity
z Capture fly ash and bottom ash
z Beneficially utilize fly ash and bottom
ash if possible
z Dispose/landfill what could not be
used
Older Model
More Recently and in the Future
z Burn
coal
z Make electricity
z Increase
control NOx, SOx, and
mercury emissions
z Capture
fly ash, bottom ash, and
FGD products
z Beneficially utilize fly ash, bottom
ash, and FGD products if possible
Air Quality Control System
Baghouse Filters or
Precipitators remove Fly
Ash
Mercury Control
SOx Control
NOx Control
Focus on Air Quality Control (AQCS)
Impacts on CCP
z
Can power plants control NOx, SOx, and
mercury and maintain or produce high
quality CCP for beneficial use?
z
Depends on technology implemented
z
We Energies path includes consideration
of CCP quality and investment toward
maintaining value of beneficial use (tail
can play a part in wagging the dog)
Technologies/Strategies to Reduce NOx
z
Low NOx burners and combustion control systems (typical
at many utilities)
– Could increase potential for carbon on fly ash and cause air
entraining issues in concrete use
z
SNCR (Selective Non Catalytic Reduction) Systems
(relatively low capital investment)
– High likelihood of increasing ammonia on fly ash
– Could make fly ash unattractive for or limit its use in concrete
z
SCR (Selective Catalytic Reduction) Systems (higher capital
investment)
– Could increase ammonia on fly ash
– Could make fly ash unattractive for or limit its use in concrete
Ammonia on Fly Ash
z
Ammonia (NH3) is a colorless gas with a pungent
odor
z
NIOSH permissible exposure limit is 25 ppm
(8hrs.) with 35 ppm peak
z
At 50 ppm, slight eye and throat irritation,
coughing
z
Can volatilize from fly ash when it gets wet or is
mixed in concrete
z
Not a problem for concrete quality, but can be a
problem for end users depending on where
concrete is being placed
We Energies NOx Reduction
z
Utilize low NOx burners and combustion controls
z
Maintain and optimize systems to limit negative impacts on fly ash
(maintain low carbon fly ash – regular testing)
z
Install SCR technology at Pleasant Prairie and Oak Creek
z
Test for ammonia on fly ash and manage accordingly through
segregation and alternative uses or blending (regular testing)
z
Remove ammonia from fly ash through beneficiation technique in
future if it becomes necessary
(Ammonia Liberation Process – more to come…)
Pleasant Prairie Air Quality Control System
Selective Catalytic Reduction
(SCR)
• Removes NOx
• >90% Removal
Efficiency
• Catalytic Reaction
• Ammonia Injection
Technologies/Strategies to Reduce SOx
z
Burn lower sulfur coals (typical strategy at
many utilities)
– Can limit future coal/fuel flexibility
z
Dry Scrubber/Spray Dry Scrubber
(relatively low capital cost)
– Inject sorbent/reagent (powdered or slurry lime) into flue gas
stream to react with sulfur
– Frequently installed upstream of main fly ash removal
– Can result in fly ash being mixed with used scrubber reagent
(calcium sulfite)
– Markets for dry/spray dry scrubber products are uncertain
– Existing use of fly ash may be compromised
Dry Scrubber – Not implemented at
We Energies
Scrubber
Reagent
Injection
ESP or FF
Ash and
Scrubber
Material
We Energies SOx Reduction
z
z
z
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Install Wet Limestone, Forced Oxidation Flue Gas
Desulfurization Systems downstream of fly ash
removal equipment (currently in operation at
Pleasant Prairie)
Preserve fly ash quality
Produce FGD Gypsum with known and accepted
uses/markets
Take advantage of additional emissions
reductions (more to come…)
Wet Limestone FGD
• Primarily Removes SO2
• >90% Removal Efficiency
• Removes Particulate,
Chlorides, Fluorides and
Mercury
• Limestone Reaction
• Produces Gypsum
Pleasant Prairie Air Quality Control System
New Oak Creek Units
Discharge
Inlet
Circulating Cooling Water
from Lake Michigan
Condenser
Steam
Coal
Generator
Steam Turbine
SCR (Ammonia Injection)
Pulverizers
Steam
Generator
Fabric Filter Baghouse
Air Heater
FGD /
WESP
Air
Forced Draft
Fan
Bottom Ash Shipped for
Beneficial Reuse or Disposal
Limestone
Preparation
⋅
⋅
Water
⋅
⋅
Limestone
Fly Ash Shipped for
Beneficial Reuse or Disposal
Induced
Draft Fan
FGD
Scrubber
Dewatering
Stack
Gypsum Shipped for
Beneficial Reuse or Disposal
Technologies/Strategies to Reduce Mercury
Emissions
z
Inject a mercury sorbent (activated carbon) and
capture with common fly ash removal system
– Proven technology, relatively low capital cost
– Fly Ash becomes co-mingled with spent
mercury sorbent
– May impact ability to use fly ash in typical
concrete applications (consistent control of air
entraining agent may be compromised, color
may become an issue)
This technology was tested at Pleasant Prairie
several years ago and significant impacts were
seen on the fly ash in terms of carbon content
and impact on air entraining in concrete
PAC Injection with Fly Ash – Not
implemented on We Energies Units
Sorbent
(AC)
Injection
CEM - Hg
Measure.
ESP or FF
Ash and
Sorbent
Activated Carbon Injection – Hg Control
We Energies Mercury control at
PIPP
z
Inject a mercury sorbent (activated carbon)
DOWNSTREAM of the fly ash removal system ToxeconTM
– Preserves 99% of the fly ash captured upstream of addition of
mercury sorbent
– Capture sorbent in downstream fabric filter baghouse
– No impact on existing fly ash quality
– Preserves ability to beneficially utilize fly ash in typical
concrete applications
This technology is installed and operating at PIPP
and is part of a full scale demonstration project
TOXECON™ Configuration – Mercury Capture
Presque Isle Power Plant
TOXECON™
N
Sorbent
Injection
PJFF
Coal
Hot Side APH
Electrostatic
Precipitator
Fly Ash (99%)
Fly Ash (1%) + PAC
Another Option for Mercury Control?
z
Wet FGD scrubbers can remove large percentage
of oxidized mercury from flue gas
z
Employ techniques to oxidize mercury in flue gas
– Halogen addition (CaBr)
– Install mercury oxidizing catalyst in SCR
z
CaBr addition recently tested at Pleasant Prairie
with promising results
– Large reduction in mercury air emissions
– No measured impact on fly ash quality or use in
concrete
Additional testing is on going and being planned…stay
tuned…
FGD Scrubber Gypsum Quality
z Daily
sampling of gypsum
z Routine analysis includes:
-Moisture
-Purity (% CaSO4 - gypsum)
-Chlorides
z Operate equipment with a goal to
maintain wallboard quality gypsum
Summary - We Energies CCP Quality
Management
z
z
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z
z
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Regular sampling and testing
Involve CCP Management Companies in
plans and decisions
Maintain Plant equipment that impacts
CCP
Educate plant personnel on the impact
they can have on CCP quality
Choose AQCS technologies with minimal
impact on CCP quality and end use
Balance competing priorities
Through Quality Management, we hope to
avoid…
Lower Quality CCP’s?
zNo
users, low value?
zSolution = Change the
CCP to a material that is
needed and can be
beneficially used
(Beneficiate it)
Why Beneficiate?
z Quality
Enhancement/Consistency
z Economics
z Environmental
Economic Benefits
z Avoided
Landfill Expenses
z Additional
Revenue from
Concrete Quality Fly Ash
Produced near Market
Environmental Benefits
z Preserve
Existing Landfill
Capacity
z Reduce Need for New Landfills
z Reduce Mining and
Transportation of Coal
Environmental Benefits
z Provide
Additional Improved Fly
Ash for Concrete
– Reduce Emissions from Cement
Kilns (CO2, NOx, HCl, SOx)
– Reduce Limestone and Clay
Quarried for Portland Cement
Production
Other Benefits
z Recover
Otherwise Lost Energy
z Raw Fuel is Conserved for
Future Generations
z Higher Quality/Strength Concrete
Fly Ash Carbon (LOI) Reduction
Technologies
z Fluidized
Bed Combustion
z Electrostatic Separation
z Froth Floatation
z Ash Fuel Reburn
Ash Fuel
Reburn
Process
Patent # 5,992,336
Valley Power Plant
•Located near downtown Milwaukee
•Responsible for 280 megawatts of power for the
downtown area
•Provides all of the steam for the district heating system
•Fly Ash has LOI near 25 %, bottom ash has LOI near 40 %
Pleasant Prairie Power Plant
z
z
z
z
Wisconsin’s largest power plant (2 units)
Located near Wisconsin-Illinois border
Serves as baseload plant for system
Fly ash has LOI of less than 1%
Old System
Power Plant
Coal
Landfill
Coal
New System
Energy
Power Plant
High Carbon
Ash From
Other Plants
Building
Materials
Wet
Process
Dry Process
Typical Reburn Results
; Bottom
Ash
VAPP LOI In = 40%
PPPP LOI Out < 1%
; Fly Ash
VAPP LOI In = 25%
PPPP LOI Out < 1%
Recovering
Ash Stored In
Landfills
Coal fired power plants have
existed for several decades, but
only recently has ash utilization
become prominent.
The question is,
where is all the ash
from years past?
In Landfills!
Licensing and constructing
landfills is becoming less
attractive as an option
because:
ÎThere is less space for new
construction of landfills
ÎIncreased regulations make landfills
more expensive to license and build
ÎPeople do not want landfills to be
built near their homes or businesses
In addition to the expense of
building and maintaining landfills,
hundreds of thousands of acres of
landfills contain significant amounts
of ash that either was not or could
not be utilized.
Much of this ash has a high L.O.I.
value, and is therefore
WASTED ENERGY
Ash Recovery Process
(Patent #6,637,354)
Construction
Materials
Coal
Pleasant Prairie
Power Plant
Energy
Stored Ash
Environmental
Benefits
Ash Recovery at Former
Landfill Site
By recovering, reburning, and treating
ash from landfills:
9Landfill space is recovered and is
available for more productive uses
9Energy is recovered
9Concrete quality fly ash is produced
9Raw fuel is conserved for future
generations
P4
Ash Fuel
Reburn Results
Ash Fuel Reburn – Blended Fly Ash
z
PRB Coal typically has 5% Ash Content
4,900,000 tons coal creates 245,000 tons ash
80% as Fly Ash = 196,000 tons Fly Ash (Class C)
z
2% Ash Fuel rate is about 100,000 tons high carbon ash
addition to boiler
z
High Carbon Supplemental Ash Fuel has 80% Ash Content
100,000 tons ash fuel creates 80,000 tons of ash
80% as Fly Ash = 64,000 tons Fly Ash (Class F)
z
Therefore, 2% Ash Fuel Addition results in a blended fly
ash:
196,000 tons (C) + 64,000 tons (F) = 260,000 tons FA
75% Class C and 25% Class F Blended Fly Ash
6.00
CaO (%)
25.00
4.00
20.00
2.00
15.00
0.00
CaO (%)
Ash Fuel Addition (%)
Ash Fuel Addition (%)
8.00
30.00
8.00
6.00
90.0
4.00
70.0
Ash Fuel Addition
SiO2 & Al2O3 & Fe2O3, and SAI
110.0
2.00
50.0
SAI, 7 days (% of control)
Ash Fuel Addition (%)
0.00
SiO2 & Al2O3 & Fe2O3 (%)
Compressive Strength Versus Age – Blended Fly
Ash
12000
Compressive Strength, psi
10000
8000
No Fly Ash
35% FA
6000
25% F/75% C
50% F/50% C
75% F/25% C
4000
2000
0
1-day
7-day
28-day
Age, days
91-day
365-day
Reburn and Displaced Coal
Annual Totals
140,000
120,000
Tons
100,000
80,000
Reburn
Coal Displaced
60,000
40,000
20,000
0
2000
2001
2002
2003
Displaced more than
2,284 railcars of coal,
since 2000 !
2004
Year
2005
2006
2007
New Oak Creek Plant
Reburn Process
z Constructed
with ability to add 5%
ash fuel
z Continue beneficial use of high
carbon ash as fuel/volume reduction
z Recover previously landfilled ash for
use as fuel
z Create valuable construction
materials
Benefits of Ash Reburn
; Recover
Otherwise Lost Energy
; Preserve Existing Landfill Capacity
; Reduce Need for New Landfills
; Provide Additional Improved Fly Ash
for Concrete
; Reduce Additional CO2 and other
Emissions from Cement Production
; Avoided Cost of Landfilling
Fly Ash and Ammonia
Liberation Technology
Technologies to Manage
Ammonia
z
z
z
z
z
z
z
z
Reburning in a dedicated FBC Unit
Washing/Humidification
Ozone Treatment
Ambient Wet Aggregate Production
Reburning in an Ash Fuel System
Lightweight Aggregate Process
Ammonia Mitigation with reagent
Ammonia Liberation Process
Ammonia Removal Temperatures
Ammonium Bisulfate
434
Ammonium Sulfate
431
Ammonium Chloride
310
Ferric Ammonium Sulfate
166
143
Ammonium Bicarbonate
Ammonium Carbonate
121
Ferrous Ammonium Sulfate
118
0
100
200
300
Temperature, C
400
500
Recycle Bag
House Ash
Bag House
Contaminated Air to
Scrubber, Combustion
Process, or NOx
Reduction
Filter System
Untreated Ash
Storage
Useable Ash
Heat Source
U.S. Patent
#6,755,901
Ammonia
Removal
Test
Set-up
Ammonia Liberation Process
Laboratory Results
Test #1 - ASTM C 618 Class C Fly Ash
Prior to Processing
After Processing
51 mg/kg
Less than 2 mg/kg
Test #2 - ASTM C 618 Class F Fly Ash
Prior to Processing
After Processing
170 mg/kg
Less than 2 mg/kg
Ammonia Liberation Process
Laboratory Results
180
Ammonia, mg/kg
160
140
120
100
80
60
40
20
0
ASTM C 618 Class C Fly Ash ASTM C 618 Class F Fly Ash
Before Processing
After Processing
Ammonia Liberation Process
Laboratory Results
Test #3 - ASTM C 618 Class F Fly Ash
Prior to Processing
After Processing - Bag house
After Processing - Product Bin
160 mg/kg
16 mg/kg
Less than 2 mg/kg
Ammonia Summary
ÖNOx reduction techniques can result in less
accepted CCP materials
ÖHigh ammonia ash can have serious and far
reaching financial ramifications
ÖALP process can remove undesirable effects
of NOx reduction techniques on ash, and the
undesirable financial ramifications
We Energies Fly Ash and Sorbent
Mercury Removal Technology
z Thermal
process making use of high
temperature air slide
z Similar to Ammonia Liberation
Process
z Released mercury captured in a
mercury condenser and scrubber
system
Mercury Removal Benefits
z Potential
to re-use expensive sorbent
material
z Maintain fly ash availability as a raw
feed material for cement manufacture
Summary
z
z
z
z
CCP quality management processes are in place
between We Energies and their CCP management
companies
Changes in response to emission control
requirements and equipment may impact some CCP
producers and end users nationally and regionally
Emission controls can be implemented while
minimizing the impact on CCP quality
CCP beneficiation technologies exist or are being
developed to address potential issues with CCP
A reliable supply of high quality CCP will continue to
exist despite some bumps in the path
“We believe that a profitable company
is truly successful when it also
excels at serving people and
protecting the environment. Our
program for using coal combustion
products is one of the ways we meet
this responsibility. We are honored
to receive the Edison Award.”
Gale Klappa
Chairman, President and CEO
Wisconsin Energy Corporation
Thank you
Questions?
Pleasant Prairie Air Quality Control System
CO2 Capture at Pleasant Prairie
z Demonstration
project
-Alstom Power
-EPRI
-We Energies (Host Site)
z Chilled ammonia technology
z 1% of flue gas from 1 boiler
CO2 Capture Process
z Cool
and condition flue gas
z CO2 removed through contact with
ammonium carbonate solution
z Solution with CO2 is heated under
pressure to remove CO2
z Solution is recycled in system
z CO2 compressed for alternate use